Extracellular vesicles and particles impact the systemic landscape of cancer

Small Extracellular Vesicles From Infarcted and Failing Heart Accelerate Tumor Growth

BACKGROUND

Myocardial infarction (MI) and heart failure are associated with an increased incidence of cancer. However, the mechanism is complex and unclear. Here, we aimed to test our hypothesis that cardiac small extracellular vesicles (sEVs), particularly cardiac mesenchymal stromal cell-derived sEVs (cMSC-sEVs), contribute to the link between post-MI left ventricular dysfunction (LVD) and cancer.

METHODS

We purified and characterized sEVs from post-MI hearts and cultured cMSCs. Then, we analyzed cMSC-EV cargo and proneoplastic effects on several lines of cancer cells, macrophages, and endothelial cells. Next, we modeled heterotopic and orthotopic lung and breast cancer tumors in mice with post-MI LVD. We transferred cMSC-sEVs to assess sEV biodistribution and its effect on tumor growth. Finally, we tested the effects of sEV depletion and spironolactone treatment on cMSC-EV release and tumor growth.

RESULTS

Post-MI hearts, particularly cMSCs, produced more sEVs with proneoplastic cargo than nonfailing hearts did. Proteomic analysis revealed unique protein profiles and higher quantities of tumor-promoting cytokines, proteins, and microRNAs in cMSC-sEVs from post-MI hearts. The proneoplastic effects of cMSC-sEVs varied with different types of cancer, with lung and colon cancers being more affected than melanoma and breast cancer cell lines. Post-MI cMSC-sEVs also activated resting macrophages into proangiogenic and protumorigenic states in vitro. At 28-day follow-up, mice with post-MI LVD developed larger heterotopic and orthotopic lung tumors than did sham-MI mice. Adoptive transfer of cMSC-sEVs from post-MI hearts accelerated the growth of heterotopic and orthotopic lung tumors, and biodistribution analysis revealed accumulating cMSC-sEVs in tumor cells along with accelerated tumor cell proliferation. sEV depletion reduced the tumor-promoting effects of MI, and adoptive transfer of cMSC-sEVs from post-MI hearts partially restored these effects. Finally, spironolactone treatment reduced the number of cMSC-sEVs and suppressed tumor growth during post-MI LVD.

CONCLUSIONS

Cardiac sEVs, specifically cMSC-sEVs from post-MI hearts, carry multiple protumorigenic factors. Uptake of cMSC-sEVs by cancer cells accelerates tumor growth. Treatment with spironolactone significantly reduces accelerated tumor growth after MI. Our results provide new insight into the mechanism connecting post-MI LVD to cancer and propose a translational option to mitigate this deadly association.

Thermotolerance in S. cerevisiae as a model to study extracellular vesicle biology

The budding yeast Saccharomyces cerevisiae is a proven model organism for elucidating conserved eukaryotic biology, but to date its extracellular vesicle (EV) biology is understudied. Here, we show yeast transmit information through the extracellular medium that increases survival when confronted with heat stress and demonstrate the EV-enriched samples mediate this thermotolerance transfer. These samples contain vesicle-like particles that are exosome-sized and disrupting exosome biogenesis by targeting endosomal sorting complexes required for transport (ESCRT) machinery inhibits thermotolerance transfer. We find that Bro1, the yeast ortholog of the human exosome biomarker ALIX, is present in EV samples, and use Bro1 tagged with green fluorescent protein (GFP) to track EV release and uptake by endocytosis. Proteomics analysis reveals that heat shock protein 70 (HSP70) family proteins are enriched in EV samples that provide thermotolerance. We confirm the presence of the HSP70 ortholog stress-seventy subunit A2 (Ssa2) in EV samples and find that mutant yeast cells lacking SSA2 produce EVs but they fail to transfer thermotolerance. We conclude that Ssa2 within exosomes shared between yeast cells contributes to thermotolerance. Through this work, we advance Saccharomyces cerevisiae as an emerging model organism for elucidating molecular details of eukaryotic EV biology and establish a role for exosomes in heat stress and proteostasis that seems to be evolutionarily conserved.

Decoding bioactive signals of the RNA secretome: the cell-free messenger RNA catalogue

Despite gene-expression profiling being one of the most common methods to evaluate molecular dysregulation in tissues, the utilization of cell-free messenger RNA (cf-mRNA) as a blood-based non-invasive biomarker analyte has been limited compared to other RNA classes. Recent advancements in low-input RNA-sequencing and normalization techniques, however, have enabled characterization as well as accurate quantification of cf-mRNAs allowing direct pathological insights. The molecular profile of the cell-free transcriptome in multiple diseases has subsequently been characterized including, prenatal diseases, neurological disorders, liver diseases and cancers suggesting this biological compartment may serve as a disease agnostic platform. With mRNAs packaged in a myriad of extracellular vesicles and particles, these signals may be used to develop clinically actionable, non-invasive disease biomarkers. Here, we summarize the recent scientific developments of extracellular mRNA, biology of extracellular mRNA carriers, clinical utility of cf-mRNA as disease biomarkers, as well as proposed functions in cell and tissue pathophysiology.

Native and engineered extracellular vesicles: novel tools for treating liver disease

Liver diseases are classified as acute liver damage and chronic liver disease, with recurring liver damage causing liver fibrosis and progression to cirrhosis and hepatoma. Liver transplantation is the only effective treatment for end-stage liver diseases; therefore, novel therapies are required. Extracellular vesicles (EVs) are endogenous nanocarriers involved in cell-to-cell communication that play important roles in immune regulation, tissue repair and regeneration. Native EVs can potentially be used for various liver diseases owing to their high biocompatibility, low immunogenicity and tissue permeability and engineered EVs with surface modification or cargo loading could further optimize therapeutic effects. In this review, we firstly introduced the mechanisms and effects of native EVs derived from different cells and tissues to treat liver diseases of different etiologies. Additionally, we summarized the possible methods to facilitate liver targeting and improve cargo-loading efficiency. In the treatment of liver disease, the detailed engineered methods and the latest delivery strategies were also discussed. Finally, we pointed out the limitations and challenges of EVs for future development and applications. We hope that this review could provide a useful reference for the development of EVs and promote the clinical translation.

Diversity of Intercellular Communication Modes: A Cancer Biology Perspective

From the moment a cell is on the path to malignant transformation, its interaction with other cells from the microenvironment becomes altered. The flow of molecular information is at the heart of the cellular and systemic fate in tumors, and various processes participate in conveying key molecular information from or to certain cancer cells. For instance, the loss of tight junction molecules is part of the signal sent to cancer cells so that they are no longer bound to the primary tumors and are thus free to travel and metastasize. Upon the targeting of a single cell by a therapeutic drug, gap junctions are able to communicate death information to by-standing cells. The discovery of the importance of novel modes of cell-cell communication such as different types of extracellular vesicles or tunneling nanotubes is changing the way scientists look at these processes. However, are they all actively involved in different contexts at the same time or are they recruited to fulfill specific tasks? What does the multiplicity of modes mean for the overall progression of the disease? Here, we extend an open invitation to think about the overall significance of these questions, rather than engage in an elusive attempt at a systematic repertory of the mechanisms at play.

Proteomic analysis of ascitic extracellular vesicles describes tumour microenvironment and predicts patient survival in ovarian cancer

High-grade serous carcinoma of the ovary, fallopian tube and peritoneum (HGSC), the most common type of ovarian cancer, ranks among the deadliest malignancies. Many HGSC patients have excess fluid in the peritoneum called ascites. Ascites is a tumour microenvironment (TME) containing various cells, proteins and extracellular vesicles (EVs). We isolated EVs from patients' ascites by orthogonal methods and analyzed them by mass spectrometry. We identified not only a set of 'core ascitic EV-associated proteins' but also defined their subset unique to HGSC ascites. Using single-cell RNA sequencing data, we mapped the origin of HGSC-specific EVs to different types of cells present in ascites. Surprisingly, EVs did not come predominantly from tumour cells but from non-malignant cell types such as macrophages and fibroblasts. Flow cytometry of ascitic cells in combination with analysis of EV protein composition in matched samples showed that analysis of cell type-specific EV markers in HGSC has more substantial prognostic potential than analysis of ascitic cells. To conclude, we provide evidence that proteomic analysis of EVs can define the cellular composition of HGSC TME. This finding opens numerous avenues both for a better understanding of EV's role in tumour promotion/prevention and for improved HGSC diagnostics.

Limiting Brownian Motion to Enhance Immunogold Phenotyping and Superimpose Optical and Non-Optical Single-EP Analyses

Optical and non-optical techniques propelled the field of single extracellular particle (EP) research through phenotypic and morphological analyses, revealing the similarities, differences, and co-isolation of EP subpopulations. Overcoming the challenges of optical and non-optical techniques motivates the use of orthogonal techniques while analyzing extracellular particles (EPs), which require varying concentrations and preparations. Herein, we introduce the nano-positioning matrix (NPMx) technique capable of superimposing optical and non-optical modalities for a single-EP orthogonal analysis. The NPMx technique is realized by ultraviolet-mediated micropatterning to reduce the stochasticity of Brownian motion. While providing a systematic orthogonal measurement of a single EP via total internal reflection fluorescence microscopy and transmission electron microscopy, the NPMx technique is compatible with low-yield samples and can be utilized for non-biased electrostatic capture and enhanced positive immunogold sorting. The success of the NPMx technique thus provides a novel platform by marrying already trusted optical and non-optical techniques at a single-EP resolution.

Modelling the complex nature of the tumor microenvironment: 3D tumor spheroids as an evolving tool

Cancer remains a serious burden in society and while the pace in the development of novel and more effective therapeutics is increasing, testing platforms that faithfully mimic the tumor microenvironment are lacking. With a clear shift from animal models to more complex in vitro 3D systems, spheroids emerge as strong options in this regard. Years of development have allowed spheroid-based models to better reproduce the biomechanical cues that are observed in the tumor-associated extracellular matrix (ECM) and cellular interactions that occur in both a cell-cell and cell-ECM manner. Here, we summarize some of the key cellular interactions that drive tumor development, progression and invasion, and how successfully are these interactions recapitulated in 3D spheroid models currently in use in the field. We finish by speculating on future advancements in the field and on how these can shape the relevance of spherical 3D models for tumor modelling.

Towards the Clinical Implementation of Extracellular Vesicle-Based Biomarker Assays for Cancer

BACKGROUND

Substantial research has been devoted to elucidating the role of extracellular vesicles (EVs) in the different hallmarks of cancer. Consequently, EVs are increasingly explored as a source of cancer biomarkers in body fluids. However, the heterogeneity in EVs, the complexity of body fluids, and the diversity in methods available for EV analysis, challenge the development and translation of EV-based biomarker assays.

CONTENT

Essential steps in EV-associated biomarker development are emphasized covering biobanking, biomarker discovery, verification and validation, and clinical implementation. A meticulous study design is essential and ideally results from close interactions between clinicians and EV researchers. A plethora of different EV preparation protocols exists which warrants quality control and transparency to ensure reproducibility and thus enable verification of EV-associated biomarker candidates identified in the discovery phase in subsequent independent cohorts. The development of an EV-associated biomarker assay requires thorough analytical and clinical validation. Finally, regulatory affairs must be considered for clinical implementation of EV-based biomarker assays.

SUMMARY

In this review, the current challenges that prevent us from exploiting the full potential of EV-based biomarker assays are identified. Guidelines and tools to overcome these hurdles are highlighted and are crucial to advance EV-based biomarker assays into clinical use.

Secretome Analysis: Reading Cellular Sign Language to Understand Intercellular Communication

A significant portion of mammalian proteomes is secreted to the extracellular space to fulfill crucial roles in cell-to-cell communication. To best recapitulate the intricate and multi-faceted crosstalk between cells in a live organism, there is an ever-increasing need for methods to study protein secretion in model systems that include multiple cell types. In addition, posttranslational modifications further expand the complexity and versatility of cellular communication. This review aims to summarize recent strategies and model systems that employ cellular coculture, chemical biology tools, protein enrichment, and proteomic methods to characterize the composition and function of cellular secretomes. This is all geared towards gaining better understanding of organismal biology in vivo mediated by secretory signaling.

Comparative Study of Metastasis Suppression Effects of Extracellular Vesicles Derived from Anaplastic Cell Lines, Nanog-Overexpressing Melanoma, and Induced Pluripotent Stem Cells

Previous studies have demonstrated that extracellular vesicles (EVs) derived from an anaplastic mouse melanoma cell line made using Nanog overexpression of F10 (Nanog+F10) suppressed the metastasis of Nanog+F10. Here, an induced pluripotent stem (iPS) cell line was focused as a more anaplastic cell line, potentially producing EVs with higher metastasis-suppressive effects. The EVs were introduced into the tail vein nine times before introducing Nanog+F10 cells. Two weeks later, the liver and lung were resected and metastatic colonies were quantified. The involvement of macrophages (invasion inhibiting ability, phagocytic activity) and cytotoxic T cells (cytotoxicity) was evaluated using J774.1 and CTLL-2 cell lines. iPS EVs showed similar level effects to Nanog+F10 EVs in every item relevant to metastasis suppression. Differential expression analysis of miRNAs in EVs and functional network database analysis revealed that dominant regulatory miRNAs were predicted. The candidate hub genes most highly associated with the metastasis suppression mechanism were predicted as six genes, including Trp53 and Hif1a, for Nanog+F10 EVs and ten genes, including Ins1 and Kitl, for iPS EVs. Regarding the mechanism, Nanog+F10 EVs and iPS EVs were very different. This suggests synergistic effect when used together as metastasis preventive vaccine.

Tumor microenvironment, histone modifications, and myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) are important components of the tumor microenvironment (TME), which drive the tumor immune escape by inducing immunosuppression. The expansion and function of MDSCs are tightly associated with signaling pathways induced by molecules from tumor cells, stromal cells, and activated immune cells in the TME. Although these pathways have been well-characterized, the understanding of the epigenetic regulators involved is incomplete. Since histone modifications are the most studied epigenetic changes in MDSCs, we summarize current knowledge on the role of histone modifications in MDSCs within this review. We first discuss the influence of the TME on histone modifications in MDSCs, with an emphasis on histone modifications and modifiers that direct MDSC differentiation and function. Furthermore, we highlight current epigenetic interventions that can reverse MDSC-induced immunosuppression by modulating histone modifications and discuss future research directions to fully appreciate the role of histone modifications in MDSCs.

Exosomal noncoding RNA-mediated spatiotemporal regulation of lipid metabolism: Implications in immune evasion and chronic inflammation

The hallmark of chronic inflammatory diseases is immune evasion. Successful immune evasion involves numerous mechanisms to suppress both adaptive and innate immune responses. Either direct contact between cells or paracrine signaling triggers these responses. Exosomes are critical drivers of these interactions and exhibit both immunogenic and immune evasion properties during the development and progression of various chronic inflammatory diseases. Exosomes carry diverse molecular cargo, including lipids, proteins, and RNAs that are crucial for immunomodulation. Moreover, recent studies have revealed that exosomes and their cargo-loaded molecules are extensively involved in lipid remodeling and metabolism during immune surveillance and disease. Many studies have also shown the involvement of lipids in controlling immune cell activities and their crucial upstream functions in regulating inflammasome activation, suggesting that any perturbation in lipid metabolism results in abnormal immune responses. Strikingly, the expanded immunometabolic reprogramming capacities of exosomes and their contents provided insights into the novel mechanisms behind the prophylaxis of inflammatory diseases. By summarizing the tremendous therapeutic potential of exosomes, this review emphasizes the role of exosome-derived noncoding RNAs in regulating immune responses through the modulation of lipid metabolism and their promising therapeutic applications.

Extracellular vesicles and particles as mediators of long-range communication in cancer: connecting biological function to clinical applications

Over the past decade, extracellular vesicles and particles (EVPs) have emerged as critical mediators of intercellular communication, participating in numerous physiological and pathological processes. In the context of cancer, EVPs exert local effects, such as increased invasiveness, motility, and reprogramming of tumor stroma, as well as systemic effects, including pre-metastatic niche formation, determining organotropism, promoting metastasis and altering the homeostasis of various organs and systems, such as the liver, muscle, and circulatory system. This review provides an overview of the critical advances in EVP research during the past decade, highlighting the heterogeneity of EVPs, their roles in intercellular communication, cancer progression, and metastasis. Moreover, the clinical potential of systemic EVPs as useful cancer biomarkers and therapeutic agents is explored. Last but not least, the progress in EVP analysis technologies that have facilitated these discoveries is discussed, which may further propel EVP research in the future.

Tumor-derived nanoseeds condition the soil for metastatic organotropism

Primary tumors secrete a variety of factors to turn distant microenvironments into favorable and fertile 'soil' for subsequent metastases. Among these 'seeding' factors that initiate pre-metastatic niche (PMN) formation, tumor-derived extracellular vesicles (EVs) are of particular interest as tumor EVs can direct organotropism depending on their surface integrin profiles. In addition, EVs also contain versatile, bioactive cargo, which include proteins, metabolites, lipids, RNA, and DNA fragments. The cargo incorporated into EVs is collectively shed from cancer cells and cancer-associated stromal cells. Increased understanding of how tumor EVs promote PMN establishment and detection of EVs in bodily fluids highlight how tumor EVs could serve as potential diagnostic and prognostic biomarkers, as well as provide a therapeutic target for metastasis prevention. This review focuses on tumor-derived EVs and how they direct organotropism and subsequently modulate stromal and immune microenvironments at distal sites to facilitate PMN formation. We also outline the progress made thus far towards clinical applications of tumor EVs.

The covert symphony: cellular and molecular accomplices in breast cancer metastasis

Breast cancer has emerged as the most commonly diagnosed cancer and primary cause of cancer-related deaths among women worldwide. Although significant progress has been made in targeting the primary tumor, the effectiveness of systemic treatments to prevent metastasis remains limited. Metastatic disease continues to be the predominant factor leading to fatality in the majority of breast cancer patients. The existence of a prolonged latency period between initial treatment and eventual recurrence in certain patients indicates that tumors can both adapt to and interact with the systemic environment of the host, facilitating and sustaining the progression of the disease. In order to identify potential therapeutic interventions for metastasis, it will be crucial to gain a comprehensive framework surrounding the mechanisms driving the growth, survival, and spread of tumor cells, as well as their interaction with supporting cells of the microenvironment. This review aims to consolidate recent discoveries concerning critical aspects of breast cancer metastasis, encompassing the intricate network of cells, molecules, and physical factors that contribute to metastasis, as well as the molecular mechanisms governing cancer dormancy.

Weaving the nest: extracellular matrix roles in pre-metastatic niche formation

The discovery that primary tumors condition distant organ sites of future metastasis for seeding by disseminating tumor cells through a process described as the pre-metastatic niche (PMN) formation revolutionized our understanding of cancer progression and opened new avenues for therapeutic interventions. Given the inherent inefficiency of metastasis, PMN generation is crucial to ensure the survival of rare tumor cells in the otherwise hostile environments of metastatic organs. Early on, it was recognized that preparing the "soil" of the distal organ to support the outgrowth of metastatic cells is the initiating event in PMN development, achieved through the remodeling of the organ's extracellular matrix (ECM). Remote restructuring of ECM at future sites of metastasis under the influence of primary tumor-secreted factors is an iterative process orchestrated through the crosstalk between resident stromal cells, such as fibroblasts, epithelial and endothelial cells, and recruited innate immune cells. In this review, we will explore the ECM changes, cellular effectors, and the mechanisms of ECM remodeling throughout PMN progression, as well as its impact on shaping the PMN and ultimately promoting metastasis. Moreover, we highlight the clinical and translational implications of PMN ECM changes and opportunities for therapeutically targeting the ECM to hinder PMN formation.

Tumour extracellular vesicles and particles induce liver metabolic dysfunction

Cancer alters the function of multiple organs beyond those targeted by metastasis1,2. Here we show that inflammation, fatty liver and dysregulated metabolism are hallmarks of systemically affected livers in mouse models and in patients with extrahepatic metastasis. We identified tumour-derived extracellular vesicles and particles (EVPs) as crucial mediators of cancer-induced hepatic reprogramming, which could be reversed by reducing tumour EVP secretion via depletion of Rab27a. All EVP subpopulations, exosomes and principally exomeres, could dysregulate hepatic function. The fatty acid cargo of tumour EVPs-particularly palmitic acid-induced secretion of tumour necrosis factor (TNF) by Kupffer cells, generating a pro-inflammatory microenvironment, suppressing fatty acid metabolism and oxidative phosphorylation, and promoting fatty liver formation. Notably, Kupffer cell ablation or TNF blockade markedly decreased tumour-induced fatty liver generation. Tumour implantation or pre-treatment with tumour EVPs diminished cytochrome P450 gene expression and attenuated drug metabolism in a TNF-dependent manner. We also observed fatty liver and decreased cytochrome P450 expression at diagnosis in tumour-free livers of patients with pancreatic cancer who later developed extrahepatic metastasis, highlighting the clinical relevance of our findings. Notably, tumour EVP education enhanced side effects of chemotherapy, including bone marrow suppression and cardiotoxicity, suggesting that metabolic reprogramming of the liver by tumour-derived EVPs may limit chemotherapy tolerance in patients with cancer. Our results reveal how tumour-derived EVPs dysregulate hepatic function and their targetable potential, alongside TNF inhibition, for preventing fatty liver formation and enhancing the efficacy of chemotherapy.

Ceramide present in cholangiocarcinoma-derived extracellular vesicle induces a pro-inflammatory state in monocytes

Cholangiocarcinoma (CCA) is a rare cancer characterized by a global increasing incidence. Extracellular vesicles (EV) contribute to many of the hallmarks of cancer through transfer of their cargo molecules. The sphingolipid (SPL) profile of intrahepatic CCA (iCCA)-derived EVs was characterized by liquid chromatography-tandem mass spectrometry analysis. The effect of iCCA-derived EVs as mediators of inflammation was assessed on monocytes by flow cytometry. iCCA-derived EVs showed downregulation of all SPL species. Of note, poorly-differentiated iCCA-derived EVs showed a higher ceramide and dihydroceramide content compared with moderately-differentiated iCCA-derived EVs. Of note, higher dihydroceramide content was associated with vascular invasion. Cancer-derived EVs induced the release of pro-inflammatory cytokines in monocytes. Inhibition of synthesis of ceramide with Myriocin, a specific inhibitor of the serine palmitoyl transferase, reduced the pro-inflammatory activity of iCCA-derived EVs, demonstrating a role for ceramide as mediator of inflammation in iCCA. In conclusion, iCCA-derived EVs may promote iCCA progression by exporting the excess of pro-apoptotic and pro-inflammatory ceramides.

Comprehensive isolation of extracellular vesicles and nanoparticles

There is an increasing appreciation for the heterogeneous nature of extracellular vesicles (EVs). In addition, two nonvesicular extracellular nanoparticles (NVEPs), exomeres and supermeres, have been discovered recently that are enriched in many cargo previously ascribed to EVs. The EV field has largely focused on EV isolation and characterization, while studies on NVEPs are limited. At this juncture, it is critically important to have robust and reliable methods to separate distinct populations of EVs and NVEPs to assign cargo to their correct carrier. Here, we provide a comprehensive step-by-step protocol for sequential isolation of large and small EVs, nonvesicular fractions, exomeres and supermeres from the same starting material. We describe in detail the use of differential ultracentrifugation, filtration, concentration and high-resolution density-gradient fractionation to obtain purified fractions of distinct populations of EVs and NVEPs. This protocol allows assignment and enrichment of a biomolecule of interest to its specific extracellular compartment. Compared to other isolation methods, our protocol has unique advantages, including high purity and reproducibility, with minimal expertise required. The protocol can be applied to purification of EVs and NVEPs from cell culture medium and human plasma and requires ~72 h to complete. Adoption of this protocol will help translational investigators identify potential circulating biomarkers and therapeutic targets for a host of human diseases and allow basic scientists to better understand EV and NVEP biogenesis and function. Overall, this protocol will allow those interested in isolating EVs and extracellular particles to advance scientific inquiry to answer outstanding questions in the field.

Analyses of single extracellular vesicles from non-small lung cancer cells to reveal effects of epidermal growth factor receptor inhibitor treatments

Precision cancer medicine has changed the treatment landscape of non-small cell lung cancer (NSCLC) as illustrated by the introduction of tyrosine kinase inhibitors (TKIs) towards mutated epidermal growth factor receptor (EGFR). However, as responses to EGFR-TKIs are heterogenous among NSCLC patients, there is a need for ways to early monitor changes in treatment response in a non-invasive way e.g., in patient's blood samples. Recently, extracellular vesicles (EVs) have been identified as a source of tumor biomarkers which could improve on non-invasive liquid biopsy-based diagnosis of cancer. However, the heterogeneity in EVs is high. Putative biomarker candidates may be hidden in the differential expression of membrane proteins in a subset of EVs hard to identify using bulk techniques. Using a fluorescence-based approach, we demonstrate that a single-EV technique can detect alterations in EV surface protein profiles. We analyzed EVs isolated from an EGFR-mutant NSCLC cell line, which is refractory to EGFR-TKIs erlotinib and responsive to osimertinib, before and after treatment with these drugs and after cisplatin chemotherapy. We studied expression level of five proteins; two tetraspanins (CD9, CD81), and three markers of interest in lung cancer (EGFR, programmed death-ligand 1 (PD-L1), human epidermal growth factor receptor 2 (HER2)). The data reveal alterations induced by the osimertinib treatment compared to the other two treatments. These include the growth of the PD-L1/HER2-positive EV population, with the largest increase in vesicles exclusively expressing one of the two proteins. The expression level per EV decreased for these markers. On the other hand, both the TKIs had a similar effect on the EGFR-positive EV population.

The evolving tumor microenvironment: From cancer initiation to metastatic outgrowth

Cancers represent complex ecosystems comprising tumor cells and a multitude of non-cancerous cells, embedded in an altered extracellular matrix. The tumor microenvironment (TME) includes diverse immune cell types, cancer-associated fibroblasts, endothelial cells, pericytes, and various additional tissue-resident cell types. These host cells were once considered bystanders of tumorigenesis but are now known to play critical roles in the pathogenesis of cancer. The cellular composition and functional state of the TME can differ extensively depending on the organ in which the tumor arises, the intrinsic features of cancer cells, the tumor stage, and patient characteristics. Here, we review the importance of the TME in each stage of cancer progression, from tumor initiation, progression, invasion, and intravasation to metastatic dissemination and outgrowth. Understanding the complex interplay between tumor cell-intrinsic, cell-extrinsic, and systemic mediators of disease progression is critical for the rational development of effective anti-cancer treatments.

Exosomal cargos-mediated metabolic reprogramming in tumor microenvironment

Metabolic reprogramming is one of the hallmarks of cancer. As nutrients are scarce in the tumor microenvironment (TME), tumor cells adopt multiple metabolic adaptations to meet their growth requirements. Metabolic reprogramming is not only present in tumor cells, but exosomal cargos mediates intercellular communication between tumor cells and non-tumor cells in the TME, inducing metabolic remodeling to create an outpost of microvascular enrichment and immune escape. Here, we highlight the composition and characteristics of TME, meanwhile summarize the components of exosomal cargos and their corresponding sorting mode. Functionally, these exosomal cargos-mediated metabolic reprogramming improves the "soil" for tumor growth and metastasis. Moreover, we discuss the abnormal tumor metabolism targeted by exosomal cargos and its potential antitumor therapy. In conclusion, this review updates the current role of exosomal cargos in TME metabolic reprogramming and enriches the future application scenarios of exosomes.

Membrane Protein Modification Modulates Big and Small Extracellular Vesicle Biodistribution and Tumorigenic Potential in Breast Cancers In Vivo

Extracellular vesicles (EVs) are released by cells to mediate intercellular communication under pathological and physiological conditions. While small EVs (sEVs; <100-200 nm, exosomes) are intensely investigated, the properties and functions of medium and large EVs (big EVs (bEVs); >200 nm, microvesicles) are less well explored. Here, bEVs and sEVs are identified as distinct EV populations, and it is determined that bEVs are released in a greater bEV:sEV ratio in the aggressive human triple-negative breast cancer (TNBC) subtype. PalmGRET, bioluminescence-resonance-energy-transfer (BRET)-based EV reporter, reveals dose-dependent EV biodistribution at nonlethal and physiological EV dosages, as compared to lipophilic fluorescent dyes. Remarkably, the bEVs and sEVs exhibit unique biodistribution profiles, yet individually promote in vivo tumor growth in a syngeneic immunocompetent TNBC breast tumor murine model. The bEVs and sEVs share mass-spectrometry-identified tumor-progression-associated EV surface membrane proteins (tpEVSurfMEMs), which include solute carrier family 29 member 1, Cd9, and Cd44. tpEVSurfMEM depletion attenuates EV lung organotropism, alters biodistribution, and reduces protumorigenic potential. This study identifies distinct in vivo property and function of bEVs and sEVs in breast cancer, which suggest the significant role of bEVs in diseases, diagnostic and therapeutic applications.

A new paradigm for epidermal growth factor receptor expression exists in PTC and NIFTP regulated by microRNAs

Intoduction

Identification of molecular alterations associated with tumor behavior is necessary to guide clinical management. The 2022 WHO classification has organized the thyroid follicular cell-derived neoplasms into benign, low-risk and high-risk neoplasms, and emphasized the value of biomarkers that may provide differential diagnostic and prognostic information to avoid overtreatment of low risk neoplasms. This work aims to study the epidermal growth factor receptor (EGFR) expression, functional and spatial dynamics in relation to specific miRNAs alterations in papillary thyroid cancer (PTC) and in non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) considered as models of high-risk and low-risk thyroid tumors respectively.

Methods

Primary thyroid cultured cells were used for miRNA gain/loss of function and luciferase reporter assays. Paraffin embedded tissues were used for real time PCR, immuno-fluorescence stain and confocal microscopy experiments.

Results

Our results showed that in PTC, EGFR mRNA is reduced as an effect of miR-146b-5p upregulation. The EGF expression is low and the ERK pathway is inhibited. The EGFR protein high cytoplasmic expression and colocalization with the endosomal/exosomal markers, ALIX and CD63, suggest the occurrence of stress-induced EGFR internalization, accumulation in endosomal vesicles and secretion via exosomes. In NIFTP EGFR transcription is increased in association with downregulation of miR-7-5p and the EGFR/ERK pathway is active indicating dependence on the canonical EGFR pathway for growth.

Conclusion

Downregulation of transcript level along with cytoplasmic accumulation of undegraded protein is a new pattern of EGFR regulation associated with malignancy in thyroid. Further research is needed to elucidate the intracellular trafficking defects responsible for this specific EGFR dynamic in PTC.

TGFβ+ small extracellular vesicles from head and neck squamous cell carcinoma cells reprogram macrophages towards a pro-angiogenic phenotype

Transforming growth factor β (TGFβ) is a major component of tumor-derived small extracellular vesicles (TEX) in cancer patients. Mechanisms utilized by TGFβ+ TEX to promote tumor growth and pro-tumor activities in the tumor microenvironment (TME) are largely unknown. TEX produced by head and neck squamous cell carcinoma (HNSCC) cell lines carried TGFβ and angiogenesis-promoting proteins. TGFβ+ TEX stimulated macrophage chemotaxis without a notable M1/M2 phenotype shift and reprogrammed primary human macrophages to a pro-angiogenic phenotype characterized by the upregulation of pro-angiogenic factors and functions. In a murine basement membrane extract plug model, TGFβ+ TEX promoted macrophage infiltration and vascularization (p < 0.001), which was blocked by using the TGFβ ligand trap mRER (p < 0.001). TGFβ+ TEX injected into mice undergoing the 4-nitroquinoline-1-oxide (4-NQO)-driven oral carcinogenesis promoted tumor angiogenesis (p < 0.05), infiltration of M2-like macrophages in the TME (p < 0.05) and ultimately tumor progression (p < 0.05). Inhibition of TGFβ signaling in TEX with mRER ameliorated these pro-tumor activities. Silencing of TGFβ emerges as a critical step in suppressing pro-angiogenic functions of TEX in HNSCC.